Hallucinating schizophrenia patients have longer left arcuate fasciculus fiber tracks: a DTI tractography study

Liv E Falkenberg,René Westerhausen,Erik Johnsen,Rune Kroken,Else-Marie Løberg,Justyna Beresniewicz,Katarzyna Kazimierczak,Kristiina Kompus,Lars Ersland,Lydia Brunvoll Sandøy,Kenneth Hugdahl

doi:10.1016/j.pscychresns.2020.111088

Abstract

The arcuate fasciculus (AF) has been implicated in the pathology behind schizophrenia and auditory verbal hallucinations (AVHs). White matter tracts forming the arcuate fasciculus can be quantified and visualized using diffusion tensor imaging (DTI) tractography. Although there have been a number of studies on this topic, the results have been conflicting. Studying the underlying white matter structure of the AF could shed light on the constrains for interaction between temporal and frontal language areas in AVHs. The participants were 66 patients with a schizophrenia diagnosis, where AVHs were defined from the Positive and Negative Syndrome Scale (PANSS), and compared with a healthy control group. DTI was performed on a 3T MR scanner, and tensor estimation was done using deterministic streamline tractography. Statistical analysis of the data showed significantly longer reconstructed tracks along the AF in patients with severe and frequent AVHs, as well as an overall significant asymmetry with longer tracks in the left compared to the right side. In addition, there were significant positive correlations between PANSS scores and track length, track volume, and number of track streamlines for the posterior AF segment on the left side. It is concluded that the present DTI results may have implications for interpretations of functional imaging results.

Highlights

One of the most salient symptom in schizophrenia and psychosis spectrum disorders is auditory verbal hallucinations (AVHs) (Ford et al, 2014; Parnas, 2013; Sartorius et al, 1986)
There was in addition a significant track length asymmetry for the healthy control (HC) group with longer tracks on the left side, p = .0001, and a trend for a similar asymmetry for the AVH+ group
The results showed significant effects for the long segments of the arcuate fasciculus (AF) fiber bundle, where patients with severe and frequent hallucinations were characterized by longer reconstructed fiber tracks (TrackL) than healthy controls, and marginally so when compared to non-hallucinating patients

Summary

Introduction

One of the most salient symptom in schizophrenia and psychosis spectrum disorders is auditory verbal hallucinations (AVHs) (Ford et al, 2014; Parnas, 2013; Sartorius et al, 1986). Functional connectivity studies, using various statistical approaches such as seedvoxel correlations and independent component analysis (ICA), have added to earlier imaging studies by showing altered connectivity between auditory and language regions (see Alderson-Day et al, 2015 for a review). The existing literature is inconclusive when it comes to the direction of the alterations in AVH patients, with some studies showing an increase in specific and global connectivity Whether AVH causes increased or decreased functional grey matter connectivity is an unresolved issue (see Alderson-Day et al, 2015; Scheinost et al, 2019)

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Results

Conclusion